Enroute Climb Limit Weight

[JABBARA]

Let me try to explain with my Level 4 English

Similiar regulation which Dave mentions is also at EASA AIR OPS CAT.POL.A.215 En-route — one-engine-inoperative (OEI)

As Take off performance limited weight, take off weight canot not be more than, so that, at resultant climb or cruise weight, airplane one engine inoperative performance is unable to meet this requirement during at any (or most limiting) climb or cruise phase.

For Airbus 330, at old FCOMs VOL 3 in chapter 3.06.20, below the GROSS CEILING WITH SINGLE ENGINE OPERATION CHART page, there was an information table showing correction factors to subtract from GROSS CEILING to calculate NET CEILING. As an example from this table for GE engine, at the point where airplane cruise weight is 210t, NET CEILING is calculated as subtracting 6600 feet from GROSS CEILING (at ISA+10C). However in new FCOMs this table is removed. This is very logical because NET CEILING is a concept to be used at PLANNING PHASE for planned enroute track. What I mean, along the route, as noticing the combination of the height of each obstacle and the planned aircraft weight as approaching these obstacles should be so that, in case of engine failure, the NET CEILING as explained in regulations, should be clearing the most demanding or critical combination. If it is not clearing, then either Take off weight (payload) should be reduced or an escape route should be planned. As seen, this is a very complex calculation. Additionally, if there is also an MEL penalty which is reducing this net ceiling, the calculation becomes even more difficult and only be figured out by a computer calculation. Besides, as AIB Pilot, there is no tool, software, charts or tables in our hand to do all these calculations.

Airbus FlySmart software is only for take off performance calculation, and gives no idea about enroute pergormance. If it is ammended to calculate enroute performance as well ( I hope not), then we have to enter planned enroute track to FlySmart as well.

Therefore, I believe all these calculation (including MEL penalties to NET CEILING) are done (or should be done) by service provider of Computer Flight Plan (LIDO, JEPPESEN etc).

However, at least at the routes which I fly with A 330, even at very unlikley cruise weight around 210 t, with ISA+10 at cruise, without any MEL penalty, according to this old FCOM, net ceiling will be:
Gross ceiling 23500 (at Green dot), minus 6600 feet equals =16900 feet. And there is no terrain in any route which I fly at this elevation (16900 feet).